I took a quick look through the various enemies in the dungeon system code you posted. After seeing a beetle amongst what you'd usually expect monster wise, it reminded me of Dungeon Keeper. A good game, pretty sure I have both of 'em on GoG which were compatible with Windows 7, I'll try reinstalling it on Windows 10.

Still, if you want ideas for more variety, DK had some good ideas. War for the Overworld; its spiritual successor also had a good variety, though a lot of them were made from scratch as a bit different from generic monsters etc, and the names wouldn't have much bearing for most people.

[Edit: I started with the plural DK line, but wasn't sure and went with another. Caught it on a following link and had to use it. I was sure I recalled years past, looking at my giant torture chamber of moaning sounds, hearing that and thinking "damn, I know those words too".]